1) Answer is: there are 28 moles of hydrogen in 2.8 mol of caffeine.
Caffeine has molecular formula C₈H₁₀N₄O₂.
In one molecule of caffeine there are ten hydrogen atoms:
n(C₈H₁₀N₄O₂) : n(H) = 1 : 10.
n(C₈H₁₀N₄O₂) = 2.8 mol; amount of coffeine molecules.
2.8 mol : n(H) = 1 : 10.
n(H) = 2.8 mol · 10.
n(H) = 28 mol; amount of hydrogen atoms.
2) Answer is: there are 16 moles of carbon in 2.0 mol of caffeine.
In one molecule of caffeine (C₈H₁₀N₄O₂) there are eight carbon atoms:
n(C₈H₁₀N₄O₂) : n(C) = 1 : 8.
n(C₈H₁₀N₄O₂) = 2.0 mol; amount of the coffeine molecules.
2.0 mol : n(C) = 1 : 8.
n(C) = 2.0 mol · 8.
n(C) = 16 mol; amount of the carbon atoms.
3) Answer is: there are 1.6 moles of nitrogen in 0.4 mol of caffeine.
In one molecule of caffeine (C₈H₁₀N₄O₂) there are four nitrogen atoms:
n(C₈H₁₀N₄O₂) : n(N) = 1 : 4.
n(C₈H₁₀N₄O₂) = 0.4 mol; amount of the coffeine molecules.
0.4 mol : n(N) = 1 : 4.
n(N) = 0.4 mol · 4.
n(N) = 1.6 mol; amount of the nitrogen atoms.
4) Answer is: there are 7 moles of oxygen in 3.5 mol of caffeine.
In one molecule of caffeine (C₈H₁₀N₄O₂) there are two oxygen atoms:
n(C₈H₁₀N₄O₂) : n(O) = 1 : 2.
n(C₈H₁₀N₄O₂) = 3.5 mol; amount of the coffeine molecules.
3.5 mol : n(O) = 1 : 2.
n(O) = 3.5 mol · 2.
n(O) = 7 mol; amount of the oxygen atoms.
